Project Status: Complete
Project Participants: Alcoa, University of Queensland, Main Roads WA, WML Consultants
Project Leader: Evan Jamieson (Alcoa)
Various mineral processing operations produce large volume residues that are currently disposed of in dedicated facilities. The sand fraction from various residues, such as bauxite residue, fly ash, cement and lime kiln dusts, gypsum, iron making slags, mineral sands by-products and gold processing tailings, may serve as a useful by-product in various commercial applications if diverted prior to normal disposal. Production of this by-product sand to a standard would be branded trade mark ReSand®. One example of such a by-product is the coarse fraction of the bauxite residue produced by Alcoa in its Western Australian alumina refineries called Red Sand™.
Recent research has identified methods of separation of bauxite residue, its neutralisation through carbonation and its ability to be washed low in salt. Alcoa has produced substantial tonnages of washed and carbonated material (Red Sand™) for substitution of virgin mined sand in various trial applications. Laboratory testing in 2006 showed that ReSand® could potentially provide both commercial bulk fill (embankment construction) and pavement material to the civil construction industry, replacing the commonly used virgin mind sand and limestone.
This project focussed on two potential applications: the top-dressing of grass fields; and fill in road construction.
The first application of sand for top-dressing required a staged roll out and trial. Following significant leaching evaluation, a small trial took place and culminated in the large-scale application of sand for top-dressing of an oval. Monitoring was carried out on dust, regrowth rate, plant nutrition and uptake of metals, along with drainage water assessment.
The second application of sand was for construction of an external road. The physical properties of the sand were reviewed by Main Roads WA and the results determined where in the road profile the sand can be used – in this case the sand has been used in place of crushed lime stone. The construction works were conducted by Southern Roads Services, the contractor responsible for delivering all
maintenance and minor construction works in the state road network for the south west region of Western Australia. It was reported by the contractor that the ReSand® was easy to work and compact.
Long-term monitoring of leaching and the road structure has been carried out under the CSRP project "Monitoring of Red Sand ™ used in Greenlands Road Upgrade" (128).
Other objectives of this project were to evaluate the sustainability of Red Sand™ in the above demonstrations using the SUSOP® management technique; and also to develop certification criteria to enable ReSand® to be registered as a certification mark.